1. Field of the Invention
The present invention relates to a method and an apparatus for preventing a lock up of wheels on a moving vehicle, and a method and apparatus for evaluating the operating conditions of an antiskid control device for the moving vehicle.
2. Technical Background
The inventors of the present invention have presented an antiskid control device for preventing wheel lock up during the operation of a vehicle in a patent application (JPA, First Publication, H1-106766). This antiskid device is based on measurements of the accelerating/decelerating conditions of the wheels and their differentials, and decides whether the vehicle is in a stable antiskid control condition (i.e., generating a slipping condition which is lower than the maximum frictional condition for a road), or in an unstable operating condition (i.e., generating a slipping condition which is higher than the maximum frictional condition for the road).
However, the above antiskid device presented a problem that because the device judges the stability of the vehicle operation on the basis of the measured values of the wheel speeds and their differentials, if the wheel speed changes for some reason, caused by vibrations in the wheel due to road conditions for example, then measurement errors increased leading to erroneous judgement. Therefore, the existing antiskid control device and operating method needed improvement.